<!DOCTYPE html>
<html lang="zh">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      var year = prompt("请输入年份：")
      if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0) {
        alert(`${year}年是闰年！`)
      } else {
        alert(`${year}年不是闰年！`)
      }
    </script>
  </body>
</html>
